For a spiral loop antenna generally attached to a battery and housed in a terminal, the antenna has an antenna pattern formed in a single plane and is attached to one side of the battery.
When the size of the antenna is larger than a certain size (e.g., a size of at least 50 mm×40 mm), the use of the antenna that has a loop antenna pattern formed on a single side thereof and then is attached to a battery does not cause a problem with the performance of the antenna. However, if the size of the antenna is decreased, the performance of the antenna may be deteriorated.
This is because the smaller size of the antenna causes a problem in that a spiral loop antenna pattern formed in a single plane would not be able to exhibit sufficient antenna performance.
Accordingly, such a case requires an antenna structure that prevents deterioration of the performance of an antenna.